const redux = require('redux')
const initialState = {
	counter: 0,
}
// reducer
function reducer(state = initialState, action) {
	switch (action.type) {
		case 'INCREMENT':
			return { ...state, counter: state.counter + 1 }
		case 'DECREMENT':
			return { ...state, counter: state.counter - 1 }
		case 'ADD_NUMBER':
			return { ...state, counter: state.counter + action.num }
		case 'SUB_NUMBER':
			return { ...state, counter: state.counter - action.num }
		default:
			return state
	}
}
// store（创建的时候需要传入一个reducer）
const store = redux.createStore(reducer)

// 订阅store的修改
store.subscribe(() => {
	console.log('state 发生了改变', store.getState().counter)
})

// actions
const action1 = { type: 'INCREMENT' }
const action2 = { type: 'DECREMENT' }
const action3 = { type: 'ADD_NUMBER', num: 5 }
const action4 = { type: 'SUB_NUMBER', num: 12 }
store.dispatch(action1)
store.dispatch(action2)
store.dispatch(action3)
store.dispatch(action4)
